Hardness testing tool



July 13, 1943.

Filed Nov. l2

3 Sheets-Sheet 1 Z d F O 5 3 2M M O MW 2 Zi 1.. @E2/M /YIM r vNAWY .JY w l. ,Y 677// /VH 6 HV 7% w w w w w 3 n 4.

4 W O 11| 4. 1 e 1, 2 n 1 1 .,w/ 1- 1 m m m 4.

dlg-l INVENTOR L. J. MARKWARDT ATTORNEYS July 13, 1943. L. J. MARKWARDT l HARDNESS TESTING TOOL Filed NOV. l2, 1941 .":5 Sheets-Sheet 2 INVENTOR L. J. MARKWARDT 6i ATTORNEYS July 13, 1.943.

L. J.' MARKW/-XRDI HARDNESS TESTING TOOL l Filed NOV. ,12, 194],

3 Sheets-Sheet 3 INVENTO'R vBY 'ATTORNEYS this purpose has Patented July-13, 1943v Lorraine J. Markwardt, Madison,

to Secretary of Agriculture of the of America Wis., assigner United States Application November 12, 1941,'SerialNo. 418,658 7 claims.' (ci. 265-19) (Granted under the act of amended April 30, 1928;

inversely relatedk to the hardness. The small in' This application is made under-the act of March 3, 1883,' as amended by the act of April 30, 1928, and the invention herein described and claimed, if

patented, may be manufactured and used by orfor the Government of I theUnited States of America for governmental purposes without the payment to me of any royalty thereon.

This invention relates to devices for testing the hardness .of materials, such as wood, plastics, and other non-metallic materials.

The general object of this invention is the provision of a de'vice for testing the hardness of materials of the type mentioned which is portable, which can be operated easily, and by means of which determinations of hardness can be made rapidly and accurately.

The usual method of determining hardness of wood and such other non-metallic materials is to measure the load required to embed a steel ball in the material. The conventional steel ball for a standard ,diameter of 0.444 of an inch and in making the determination it is embedded to one-half of its diameter. This method usually requires the use of a small specimen, which must becut or otherwise taken from the material to be tested.

A specic obliect of this invention is the provision of a device of the type mentioned which does not require the removalof such a specimen and which does not materially damage the material. By the use of this invention hardness tests'can be made wherever the material is found and Whether it is a xedY part of a structure, a growing tree, or otherwise.

Individual pieces of wood differ from one another in density, hardness and other mechanical properties, even those of the same species. One of the many uses of this invention is the grading or classification of individual pieces of wood or other materials during manufacturing processes or atv other times, according tohardness and hence density, strength and mechanical properties. Conversely, the softness of Wood, as for instance, when soft or Weak pieces are desired-for carving or for other purposes. Also, it is useful ln-segregating pieces of woodthat have become softened by Jdecay or other agencies.

March 3, 1883, as 370 O. G. 757) dentures made by these points will not ordinarily 'detract from the value or usefulness of the materials tested.

The following description, considered togetherV with the accompanying drawings, will disclose this invention more fully, .its construction, arrangements and combinations of parts and other objects and advantages thereof will be apparent.

In the drawings:

Figure 1 is a side elevational view of an embodiment of this invention poised on a piece of material to be tested.

Figure 2 is a section Figure 1.

Figure 3 is a plan view from the line 3-3 of Figure 1.

Figure 4 is a section .along the line 4--4 of Figure 1. f

along the line 2 2 of VFigure 5 is a front elevational View ofa modied embodiment of this invention. Figure 6 is a fragmentary side elevational view of the modified embodiment illustrated in Figure 5.

Figures 7 and 8 are longitudinal sections of further modifications of this invention which may beused in either the embodiment illustrated in Figures 1, 2, 3, and 4 or the embodiment illustrated in Figures 5 and 6.

Figure 9 is a side elevational view, partly in'A section, of a third embodiment of this invention.

Figure 10 is a section along the line I -IU of Figure 9.

Figure 11 is Figure 9.

Referring with more particularity to Figures 1, 2, 3, and 4, the embodiment illustrated comprises a shaft or rod II, to the lower end of which is secured ar block I2. To the bottom of the block I2, pins I3, each tapered downwardly to a point Y in a common plane, are'secured parallel to the itv may be used for determiningI l In general, this invention Adeparts from the plate I4 on the rod II axis ofthe rod I I. be eitherpointed, as illustrated, or in some other form, such as a ball or atsurface, or any variation of these forms. Above the block I2, a plate I4, integral with a sleeve I5, is slidably mounted on the rod II. The slidable movement .of the is limited by means of the sleeve I5 engaging 'Ihe pins I1 longitudinal slots I6 of pin I1 projecting from the rod II.

project beyond the sleeve I5 to abut the upper` end of a coil -spring I8 under compression about i the sleeve I5, the lower end of the said spring abutting the plate I4 posts I9 are xed and they extend through a section along the line II-I I of Thel points of the pins I3 may I4. To the bottom of the plate apertures 20 in the block I2, terminating at the lower end in the same plane as the ends of the pins I3 when the block I2 and plate I4 are in contact.

Above the sleeve I5 there is slidably mounted onthe rod II a sleeve 2| integral with an outwardly extending bracket 22. The sleeve 2| is prevented from turning by means of a spline key 23 on the sleeve 2| engaging a longitudinal slot 24 on the side of the shaft II. The sleeve 2I is held downward against a fixed collar 25 on the shaft II by means of a coil spring 26 in compression about the rod II between the top of the sleeve 2| and a fixed collar 21 thereabove. The bracket 22 carries a displacement gauge 28, the operator 29 of which is normally in contact with the top of plate I4.

On top of the rod II a trip mechanism is provided which may be of any suitable conventional type. The mechanism illustrated comprises an extension 30 of the rod Il and a flange 3| at the base of the extension. A spring 32 is disposed about the extension 30 on the flange 3|. 'I'he lower end of the lower section 33 of a tubular casing 34 is disposed about the upper end of the shaft II and is provided with an annular shoulder 35 to abut the lower end of the flange 3|. The upper end of the section 33 extends to a point above the spring 32, into which there is screwed a barrel 36 about the extension 30 to abut the upper end of the spring 32.

The upper end of the extension 30 is recessed to provide an upwardly facing shoulder 31 and leave a small tip 38 at the top. A ring 39 rests on top of the barrel 36 and its top is normally flush with the shoulder 31. An upper section 40 of the tubular casing 34 is secured at the bottom to the section 33 by means of threads, substantially as shown. On top of the ring 39 a tumbler 4| is disposed to slide laterally and is provided with an aperture 42 large enough to receive the extension 30. The outside width of the tumbler is less than the inside diameter of the casing section 40 at that point and normally the tumbler is held against one side of the section 40 so that the aperture 42 is eccentric to the extension 30 and engages the shoulder 31 on one side as illustrated. The tumbler is yieldabh1 held in this position by the lower end of a leaf spring 43, the upper end of which is fastened to a bar 44 resting on top of said tumbler. The lower end of the bar 44 is provided with a longitudinal cavity 45, aligned with and of the same size as or slightly larger in diameter than the extension 3D. The inner diameter of the section 40 at a point above the cavity 45 is reduced and is in slidable relation with the bar 44.. This reduction in diameter provides a shoulder 45 downwardly facing. The section 40 extends upward beyond the end of the bar 44 and is provided with a cap 41 threadedly engaged therewith. Between the cap 41 and the upper end of the bar 44 a spring 48 is disposed for compression. n the cap 41 a knob 49 is fixed to permit the manual application of force downwardly. The side of the tumbler 4 I, in contact with thecasing section 49,

. is curved convexly so that a force applied downwardly thereon will move it inwardly to Valign the aperture 42 with the extension 30.

The embodiment described above is operated 'by placing it, as shown in Figure 1, with the bottom of the posts I9 and the points of the pins 13s-resting on the surface of the material to being tested while the posts I9 hold the plate 'I4 stationary. The force applied on the knob 49 is increased and the casing 34 moves downward, the section 40 moving over the bar 44 and the section 33 over the shaft II as cornpression in the spring increases. As the casing 44 moves downward the shoulder 46 con tacts the convex side 50 of the tumbler 4I and forces it laterally against the action of the spring 43 until theaperture 42 is in alignment or registry with the extension 30 and cavity 45. This permits the energy stored up in the spring 48 to force the bar 44 and tumbler 4I down over the end of the extension 30. The end of the extension 30 passes through the aperture 42 into the cavity 45 and receives a blow on the tip 38 by the bar 44 at the upper end of the cavity 45. Since the initial distance between the tumbler 4I and shoulder 46 is xed, the energy stored up in the spring 48 at the time shoulder 31 is disengaged from the tumbler will be constant and the same force is always delivered to the pins I3 upon each application. The magnitude of this force, however, can be varied by turning the cap 41 relative to the section 40 on the threads by which they are engaged. Consequently, the distance to which the pins I3 are embedded in the material is a function of its hardness. This distance is the same as the displacement between the shaft I movable with the pins I3, and the plate I4 held stationary by the posts I9. The relative movement between the shaft I| and plate I4 actuates the operator 29 of the gauge 28 which indicates the displacement in terms of hardness. As the shaft II moves downward relative to the plate I4, the spring I8 is compressed and when the pins I3 are removed from the material tested, the spring I8 returns the plate to its initial position. The spring 26 is strong enough to hold the sleeve 2| on the collar 25 against the upward force of the plate I4 acting through the gauge 28. The purpose of the spring 26 is to cushion the shock `of the blow delivered to the rod II and prevent damage to the delicate mechanism in the gauge 28.

As force is applied on the knob 49; the casing 34 move sdownward relative to the shaft I I. The flange 3| moves toward the barrel 35 compressing the spring 32. After the blow is delivered to the end of the extension 3U and the knob 49 released, the spring 32 returns the ange 3| to its initial position against the shoulder 35. The extension 30 is thus retracted from the cavity 45 and tumbler 4| which is moved 1ateral1y under the action of the spring 43 to engage the shoulder 31.

In Figures 5 and 6 a modified form `of the invention is illustrated. In this modification the dial gauge 5| is slidably mounted on the shaft I| above a xed collar 52 by means of sliding brackets 53 and 54 and is held in a suspended position by means of a spring 55 fastened at one end to the shaft I.| by means of a screw 56 and at the other end to the bracket 53 by means of a screw 51. 'Ihat portion of the rod II on which the bracket 54 slides has a flat side 59 which is engaged by the bracket 54 to prevent its turning on the shaft. The operator 58 of the dial gauge 5I projects downward to a point above the stationary plate I4 at a distance equal to the distance between the bracket 54 and the collar 52 so -that in the initial position when the dial gauge is moved down on the shaft I I against the action of the spring 55, the lower end of the operator 58 will contact the plate I4 at the same .time when bracket 54 contacts the collar 52.

Consequently, after the pins I3 are embedded in the material being tested, the relative displaceand` 11 -comprises a tubular casing 18, at the bottom of which is'secured a cylinder 19 having longitudinal apertures llvtherethrough, preferably ment between the shaft II and plate I4 can be determined by sliding thedial gauge 5I downward until the bracket 54 bontacts the collar 52.

In Figure 7 a further modification of this invention is shown comprising a substitution for the tripping mechanism described above. The upper end of the rod II in this modification ter-v minates in a flange 62 slidable in a cylindrical ca sing 63. Above the ange 62 a piston 64 is valso slidably mounted in the casing 63. Between the piston'64 and flange 62 a spring 65 is dis-v posed. The piston 84 is adapted to be forced downward manually by means of a knob 86' connected to the piston'by a connecting. bar 61 through the top of the casing 63. On` the exterior of the casing 64 a limit switch is mounted in a housing 68. the casing 63 and contains a pair of electrical terminals 69 and 18. `The terminal 69 lis connected to one pole of a battery 1I and the other terminal 18 is connected to one terminal of an incandescent bulb 12 mounted on the outside of `the housing 68. vThe other terminal of the bulb 12 is connected to the other pole of the battery 1I. The terminal 69 is secured to oneA end of a switch contact element 13, such as'a piece The housing 68 is fastened to four. Above the'cylinder 19 another cylinder 8| is disposed which' is slidable longitudinally within the casing 18. To the bottom of the movable cylinder 8I push pins,82 tapering downwardly are secured, there being. one pin for each aperture 88. The pins 82 are adapted to reciprocate through the apertures 8-and normally project below the bottomv of the casing 18 a predetermined distance to -a common' plane. The lower end of a guide rod 83 is secured to the `movable cylinder 8 I and the upper end of said rod slidably operates in a longitudinal aperture 84 of a spool-like member 85. The member 85 has a lower annular ange 86 against| the inner.

surface of the casing 18 and an upper threaded flange 81 adapted to engage internal threads at the upper end 'of the casing 18 to hold it securely in position. The annular space 88 between the two anges 86 and 81 is for the retention of lubricating oil which feeds through a small passage 89 of the lower flange 86 adjacent to casing 18, 'andwhich is introduced through another passage v 90 of the upper ange 81 also adjacent to casing of spring steel. Theother end of the element 13 is free and is adapted to contact the terminal 18 when it is pushed downward a predetermined distance against its'internal spring action. This is accomplished by means of a plunger 14 slidably disposed through the top of the housing 88. This plunger contacts the member 13 and is normally held upward thereby in contact with a pin -15 piston 64 through As theV projecting laterally from the a longitudinal slot 16 in the casing 63. piston moves downward relative to the casing B3, the pin 15 moves with it and urges the plunger of predetermined magnitude may lbe used with' either Vthe embodiment illustrated in vFigures 1, 2, 3, and 4, or the embodiment illustrated in Figures 5 and 6. If desired, the limit switch can be replaced by another dial gauge 11 as shown in Figure 8, so that instead of using the instrument to measure'the distance of penetration' under a given load, it can be used to measure the force required to vpenetrate the pins to a predetermined distance. In using this modication, the operator would observe the dial gauge which indicates depthof penetration until a predetermined depth is reached, and then takethe reading from the gauge 11 as an indication of the 18. About the rod 83. between the-spool 85 and cylinder 8I, a coil spring 9| is disposed. The top ofthe casing 18 on the outer side is provided with external screw threads 92 for engaging the internal threads 93 of a removable cap 94.,

' A pin 95 is fixed at one end to the cylinder 8| and extends outward laterally through a longitudinal slot 96 in the side of the casing 18. Above the pin 95 a'dial gauge is'mounted on a bracket 98 having a band 98 encircling the casing 9,8 and secured to it by means of a set screw |80.

`The operator I 0I of the dial gauge extends downward'to abut the top of the pin 95. To use the ydevice, the pins 82 are set on the surface of the material to be tested, such as the piece of wood I 02^shown in Figure 9, and a downward `force andload the spring 9|. Aacting downward against the cylinderjl tends is applied on the cap 94 causing the casing V18, together with the fspool 85, to :move downward I'he force of the spring to sink thepins 82 into thematerial being tested. The application of force on the cap 94 is continued until the bottom of the cylinder 19 contacts the surface of the material being tested. The distance to which the pins 82 become embedded depends upon the hardness of themateriall being tested.- This is determined by the displacement from the initial position between the pins 82 and the casing, as indicated by the gauge 91, whenthe bottom of the cylinder 19 is in contact with the surface `of vthe material. For very soft materials relative displacement between the force required to embed the points and hence as an index of the hardness of the material.

The embodiment illustrated in Figures 9, 10

casing and the pins from the vinitial position would be small and for hard materials such displacementA would' -be correspondingly greater.

This displacement being an index of the hardness, the gauge91 is graduated in units of hardness so that readings can be taken directly without computation.

Having'thus described my invention, I' claim:

1. A device for determining the hardnessof materials comprising a test head carrying a'group of pins adapted to penetratethe material to be tested, means for applying a force of. predetermined magnitude on said head to vforce said -pins l into .the materiahand means for determining the distance to which said pins penetrate the` material as an index'of the hardness thereof. 2. Al device for determining the hardnessv of materials comprising a test head carrying a group of pins adapted to penetrate the material to be tested, means for applying a force of predetermined magnitude on said head to force said pins into the material, a displacement gauge movable with said head, said gauge having a dependent operator, and means for holding said operator in a fixed position when said gauge moves with said head.

3. A device for determining the hardness of materials comprising a shaft, pins iixed to the end of said shaft, said pins being adapted to penetrate the material to be tested, a slidable member on said shaft, posts for supporting said member in a stationary position over the material to be tested, relative to said pins, a displacement gauge movable with said shaft, said gauge having a dependent operator abutting said slidvable member so as to be held stationary therewith, and means for applying a force of predetermined magnitude on said shaft to force said pins into the material to be tested.

4. A device for determining the hardness of materials comprising a shaft, pins fixed to the end of said shaft, said pins being adapted to penetrate the material to be tested, a displacement gauge on said shaft movable therewith, said gauge having an operator, means for holding said operator in a fixed position when said gauge moves with said pins, means for applying a sudden force of predetermined magnitude on said shaft in the direction of said pins, and yieldable-means to cushion said gauge from the shock of said sudden force.

5. A device for determining the hardness of materials comprising a test head carrying a group of pins adapted to penetrate the material to be tested, means for manually applying a force on said head to push said pins into the material a predetermined distance, and means for measuring the magnitude of the force required therefor as an index of the hardness.

6. A device for determining the hardness of materials comprising an elongated casing, pins longitudinally movable within the casing, the points of said pins projecting outwardly through one end of the casing a predetermined distance, a spring opposing retraction of the pins within the casing, and means for determining relative displacement between'said casing and said pins.

'1. A hardness testing hand tool, comprising an elongated casing, a plurality of tapered pins longitudinally movable within the casing, the points of said pins lying in a common plane and projecting outwardly through one end of the casing a predetermined distance, said casing having longitudinal slideways through the end thereof, one for each pin, to slidably engage and guide said pins, a cylinder slidable in said casing, said pins being secured to said cylinder, a longitudinal shaft having one end secured to said cylinder, a spool secured Within said casing, said spool being longitudinally spaced from said cylinder, means for adjusting the longitudinal position of said spool, said spool having a longitudinal aperture therethrough, said shaft being slidably engaged with said aperture of said spool, a coil spring disposed about said shaft between said spool and said cylinder, a gage secured to said casing, said gage having an operator to actuate the mechanism thereof, a bar secured to said cylinder and engaged with said operator, said casing having a slot through which said bar projects to engage said operator.

LORRAINE J. MARKWARDT. 

